C#利用广播实现群发功能

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
//添加的命名空间引用
using System.Net;
using System.Net.Sockets;
using System.Threading;
namespace BroadcastExample
{
public partial class FormBroacast : Form
{
delegate void AppendStringCallback(string text);
AppendStringCallback appendStringCallback;
//使用的接收端口号
private int port = 8001;
private UdpClient udpClient;
public FormBroacast()
{
InitializeComponent();
appendStringCallback = new AppendStringCallback(AppendString);
}

private void FormBroacast_Load(object sender, EventArgs e)
{
Thread myThread = new Thread(ReceiveData);
//将线程设为后台运行
myThread.IsBackground = true;
myThread.Start();
}

/// <summary>
/// 在后台运行的接收线程
/// </summary>
private void ReceiveData()
{
//在本机指定的端口接收
udpClient = new UdpClient(port);
IPEndPoint remote = null;
//接收从远程主机发送过来的信息；
while (true)
{
try
{
//关闭udpClient时此句会产生异常
byte[] bytes = udpClient.Receive(ref remote);
string str = Encoding.UTF8.GetString(bytes, 0, bytes.Length);
AppendString(string.Format("来自{0}：{1}", remote, str));
}
catch
{
//退出循环，结束线程
break;
}
}
}

/// <summary>
/// 发送消息
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void buttonSend_Click(object sender, EventArgs e)
{
UdpClient myUdpClient = new UdpClient();
try
{
//让其自动提供子网中的IP广播地址
IPEndPoint iep = new IPEndPoint(IPAddress.Broadcast, 8001);
//将发送内容转换为字节数组
byte[] bytes =Encoding.UTF8.GetBytes(textBox1.Text);
//向子网发送信息
myUdpClient.Send(bytes, bytes.Length, iep);
textBox1.Clear();
textBox1.Focus();
}
catch (Exception err)
{
MessageBox.Show(err.Message, "发送失败");
}
finally
{
myUdpClient.Close();
}
}

private void FormBroacast_FormClosing(object sender, FormClosingEventArgs e)
{
udpClient.Close();
}

private void AppendString(string text)
{
if (richTextBox1.InvokeRequired == true)
{
this.Invoke(appendStringCallback, text);
}
else
{
richTextBox1.AppendText(text + "\r\n");
}
}
}
}